The present invention relates to the field of vacuum pumps, particularly of the hand-held type disclosed in U.S. Pat. Nos. 3,612,722, 4,775,302 and 4,806,084 by the present inventor the disclosures of which are incorporated herein by reference.
Vacuum pumps are generally useful whenever a vacuum is desired, for example, to provide suction. Many types of pumps have been devised, but they often suffer from such drawbacks as complexity, expense, excessive bulk, inability to pull a suitable vacuum, and the like. The vacuum pumps of the aforesaid patents have significantly solved the need for a vacuum pump which is simple, inexpensive, lightweight, compact and portable, and one which can pull a useful vacuum.
Such hand-held vacuum pumps are particularly useful in various industries, such as the automotive industry for vacuum testing and repair, liquid sampling and the like. In the medical field such pumps have been used, for example, with vacuum extraction devices in childbirth, an aid for testing for throat blocking of choking victims, and for other uses. Vacuum pumps manufactured according to the aforesaid patents have the ability to pull a vacuum of, for example, twenty-eight inches of mercury.
Since hand-held vacuum pumps are generally operated by hand, it has been necessary in many cases to use the operator's second hand to operate a vacuum release mechanism. As will be appreciated, this can be cumbersome, especially when operating a vacuum release in a confined environment with limited maneuverability, where there may be fluids or lubricants present, or when there are time restrictions or psychological pressures. Furthermore, it may be desireable to limit the release of the vacuum in a controlled manner, and with minimal finger pressure and dexterity. One example highlighting some of these special circumstances involves the use of a vacuum release on the vessel of a vacuum based penile erection set. This is an emotionally charged situation in which frustration over cumbersome or inconvenient controls may be sufficient to adversely impact the overall usefulness of the device.
One solution to vacuum release problems is disclosed in the aforementioned U.S. Pat. No. 4,806,084. Patent '084 shows and describes a relatively simple vacuum release mechanism attached to the pump, one which can be released relatively easily by a finger of the same hand that operates the pump. However, for some applications, the '084 vacuum release may release the vacuum too quickly or require greater dexterity than possessed by the operator. Moreover, use of the '084 vacuum release could be cumbersome in that the release may not be biased to either the "on" or the "off" position. Hence the operator might become frustrated in unsuccessfully attempting to draw a vacuum in a vessel when the vacuum release was still set to the "off" position from the previous use.